| Emulsion polymerization |
The thrust behind this process is to control the dimensions of the end product which is achieved by the polymerization process within a small volume. This is done by the formation of monodisperse stable organic/aqueous droplets containing the monomeric/polymeric chains as well as the catalysts and crosslinking agents.79 Since bimolecular termination is inhibited by the spatial separation of propagating chains in emulsion polymerizations, it is possible to simultaneously achieve high rates of polymerization and create polymer with a high molecular weight,81 thereby making this methodology an effective contender for nanogel synthesis |
| Controlled/living radical polymerization |
Adding crosslinking agents allows for the synthesis of crosslinked particles or gels with a controlled polymer molecular weight in this methodology. Through the incorporation of quiescent forms in the dispersing species, the rate of bimolecular termination and lengthening of the life of the expanding polymer chains can be reduced.82 By adjusting the size and molar mass of the nano scaffolds, CLRP has proven to be effective in nanogel design wherein tuning the final morphology and structural composition such as porosity of the nanogels is possible due to the wide range of molar mass and branching structure of the nanogel building blocks that can be achieved by varying the concentrations of monomers and crosslinking agent83,84
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| Photo-induced crosslinking |
This technique is environmentally friendly as no crosslinking agents or catalysts are required, and no waste products are generated. For crosslinking, light irradiation is used on reactants that have a photo-activatable group. A photoinitiator kickstarts the reaction by being broken down by light to produce reactive radical species39,80
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| Click chemistry |
This methodology promises rapidity, adaptability, regiospecificity, high yields, and purity under aqueous reaction conditions. Oxygen, water, common organic solvents, synthesis conditions, biological substances, and pH all show high tolerance. The researchers address this ‘click’ methodology to have the potential to alter the status quo of polymeric nanogels synthesis and inspire novel approaches to the creation of polymeric drug therapies85,86
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